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1.2

Minor Versionm

by Suchitha Vishwa

Introduction

Take plastic funnels of different sizes an connect them to each other using any rubber or plastic tubing, each end connected to the neck of one of the funnels. Use this to listen to your heartbeat and measure your pulse rate.

Video Overview

    • Be careful while using the scissors and paper cutter or any other sharp tool.

    • Do not push the pipes too hard into the ears.

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  1. Cut the total length of wire into two equal halves.
    • Cut the total length of wire into two equal halves.

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    • Trim and even out the cut portion of the bottle until the diameter of the open end is between 4 cm - 5 cm.

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    • Push one blade into the bottle cap and rotate the blade to make holes( two) in the cap .

    • Insert the pipes, one in each hole.

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    • Make folds in the paper such that the width of the final fold is slightly less than the length of cut portion of the bottle.

    • The thickness of the folded paper should be enough to fill the gap between the sides of the cap and the pipes.

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    • Cut out a circular portion of cardboard and trim few millimeters off it so that it fits inside the cut portion of bottle easily.

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    • Cut out enough portion of the cardboard disc in the centre such that the paper wrapped pipes can pass through it.

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    • Cut the mouth of a balloon and stretch the balloon enough to remove any wrinkles when wrapped over the cut portion of the bottle.

    • Pull the balloon from the sides to stretch it enough,so that it is able to pick vibrations of low frequencies.

    • Make the edges of the cut portion smooth by using some tape to avoid tearing of the balloon while stretching it over the edges.

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    • Mark the thick binding wire at a distance of 18 cm - 19 cm from both the ends.

    • Bend the wire at both the marks at some angle and the length of wire between the bends should be 2 cm to 4 cm.

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    • Using the same wire, pierce both the pipes at a distance of 20 cm from the open end(the end that is not secured to the the chest piece).

    • Push the wire through the holes up along the length of pipe.

    • The wire should not protrude out from other end of the pipe. It must be below the end point of pipe.

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    • Make sure the end point of wire inside the pipe is at distance of 1 cm to 2 cm from the end of rubber pipe.

    • Bend the pipes (with wire inside it) at distance of 5 cm from the open ends.

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    • Stick any tape to the foam pieces and wrap around the ends of the rubber pipe.

    • Keep half the width of foam piece protruding out ahead of the end of pipe.

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    • You may try bending the pipes more to make them stay inside ears more firmly.

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    • Cut cardboard strips ( 5 cm x 3 cm) and using tape wrap it around the pipes to hold them together, one near the cap and another one near the Y shaped joint of the pipes.

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    • No gap should be present between the balloon and pipes within the chest piece. This will hinder the sound waves travelling through the pipes.

    • Balloon not stretched enough to create vibrations by low frequencies like of that heart beats.

    • Pipes within the chest piece not firm which makes unwanted sounds when it rubs around inside the chest piece.

    • Not enough bend in the binaural near the end which might cause pipes to come out of the ears while using.

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    • Touch the pipes with balloon and listen to the sound. Why is the sound of heart beat loud and clear enough? What is the mechanism behind the working of stethoscope?

    • Vary the gap between the pipes and the balloon diaphragm and observe the variations in sound. What should be the optimum gap between the diaphragm and pipes to hear the sound clearly?

    • Compare the heart beat sounds by placing the chest piece at the place where the heart is and on the radial artery at the elbow and near the wrist.

    • Try hearing the sounds of various frequencies( even the noise around ) with and without stethoscope. Why does it sound louder with stethoscope on?Compare the speed of sound in air and in solids.

    • Use thin plastic sheet as a diaphragm instead of balloon.What properties of the material make it suitable for being used as the diaphragm?

    • Stuff the gap between the pipes and the bottle cap with some soft materials or paper.Does the sound intensity increase or decrease?

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    • Make a stethoscope using rubber pipes with diameter less than 0.5 mm or more than 1 cm.

    • Use hard plastic sheet or polythene as the diaphragm materials.

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Finish Line

Suhail Ahanger

Member since: 05/02/2017

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54 Guides authored

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